Droops

A droop occurs when a small smooth portion of the seam extends below the bottom edge of the seam at the cover hook. This is near a false seam, but this type of defect can still be seen as a closed seam (i.e., it does not lose pressure). However, it can be seen visually and will ultimately cause a false seam if untreated.

Droops can also occur in some cases, by product entrapment in food (in particular fish) food cans.

The trouble with the droop is that if you miss it visually, it is localized so just cutting in 3 places randomly may not exhibit the issue. Here is what a droop looks like on a non-destructive 360 degree scan of the thickness and length of the can – both thickness and length graphs are affected and are higher than the maximum standard specification at the same points.